Lohmann, 1896
Trunk compact, up to 0.5 mm long (Oikopleura gracilis). Endostyle arising far from the mouth. Left lobe of the stomach with round contour. Rectum scarcely extending beyond the oral wall of the stomach. Gonads adjoining the genital wall of the stomach, and embracing it a little laterally when ripe. Tail musculature narrow.